Scroll machines are becoming increasingly popular for use as compressors in refrigeration and HVAC systems due to their capability for extremely efficient operation. Generally, scroll machines include an orbiting scroll member intermeshed with a non-orbiting scroll member to define series of compression chambers. Rotation of the orbiting scroll member relative to the non-orbiting scroll member causes the compression chambers to progressively decrease in size and cause a fluid disposed within each chamber to be compressed.
The non-orbiting scroll member seals against the orbiting scroll member to achieve compression. However, slight movement of the non-orbiting scroll member relative to the orbiting scroll member is typically permitted to account for forces acting on the non-orbiting scroll member during compression and during specific fault conditions such as liquid entering the compression chamber.
During operation, the orbiting scroll member orbits relative to the non-orbiting scroll member causing fluid to be compressed within the compression chambers. Compression of the fluid causes a force to be applied to the non-orbiting and orbiting scroll members, urging separation of the non-orbiting scroll member and the orbiting scroll member. The orbiting scroll member is conventionally attached to a motor via a driveshaft and, as such, is not permitted to axially move relative to the non-orbiting scroll member. Therefore, the non-orbiting scroll member should be able to axially move relative to the orbiting scroll member during compression to accommodate certain forces applied during compression.
Vapor injections systems may be used with scroll machines to improve efficiency. Vapor-injection systems typically extract vapor at an intermediate pressure, which is somewhat higher than suction pressure and somewhat lower than discharge pressure, and inject the extracted vapor into a compression chamber to lessen the work required to output vapor at discharge pressure.
Vapor may be introduced to a compression chamber through the non-orbiting scroll member. A conduit may extend from an external economizer heat exchanger or flash tank to the scroll machine and through the non-orbiting scroll member. The conduit may accommodate axial movement of the non-orbiting scroll member during compression to avoid damage to the conduit.
Conventional vapor-injection systems often require the conduit to extend through a top portion of the scroll machine, which necessitates extending the conduit through a discharge chamber of the scroll machine and therefore requires multiple seals. Furthermore, positioning the conduit through the top portion of the scroll machine requires precise positioning of the passage through the top potion of the scroll machine and a partition defining the discharge chamber from the suction chamber to ensure proper alignment between the conduit and the non-orbiting scroll member.
The present teachings provide a scroll compressor including a housing, a non-orbiting scroll member including a first spiral wrap, and an orbiting scroll member including a second spiral wrap. The first and second spiral wraps are interleaved to define at least one moving fluid pocket that decreases in size as it moves from a radially outer position to a radially inner position. A vapor-injection system may include a shell fitting in fluid communication with a fluid passageway of the non-orbiting scroll member via a vapor injection tube. The vapor injection tube may be fixed for movement with the non-orbiting scroll member for communicating vapor into the moving fluid pockets.